Adsorption of Methylene Blue onto chemically (Na2CO3) treated ripe betel nut fibre (TRBNF) was studied using batch adsorption process for different concentrations of dye solutions (50, 100, 150 and 200 mg/L). Experiments were carried out as a function of contact time, initial solution pH (3 to11), adsorbent dose (10 gm/L – 18 gm/L) and temperature (293, 303 and 313 K). The adsorption was favoured at neutral pH and lower temperatures. Adsorption data were well described by the Langmuir isotherm and subsequently optimised using a second-order regression model by implementing face-centred CCD of Response Surface Methodology (RSM). The adsorption process followed the pseudo-second-order kinetic model. The maximum sorption capacity (qmax) was found to be 31.25 mg/g. Thermodynamic parameters suggest that the adsorption is a typical physical process, spontaneous, enthalpy driven and exothermic in nature. The maximum adsorption occurred at pH 7.0. The effect of adsorption was studied and optimum adsorption was obtained at a TRBNF dose of15 gm/L.
Part of the book: Response Surface Methodology in Engineering Science